Percutaneous implantable nuclear prosthesis

ABSTRACT

A multi-chamber balloon for a nuclear implant has an elastomeric membrane defining inner and outer chambers integral with a valve body. The valve body includes a core portion and sealing membrane for sealing the inner and outer chambers. An assembly for manufacturing the multi-chamber balloon includes a balloon mandrel which may be dip coated in a silicone dispersion to create an elastomeric membrane for the inner and outer chambers integral with the valve body. The elastomeric membrane formed on the mandrel is partially inverted to form a coaxial elastomeric structure with the smaller inner chamber disposed within the larger outer chamber. The valve is incorporated into the inner and outer chambers to form a unitary structure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority of U.S. ProvisionalPatent Application No. 62/074,925, filed Nov. 4, 2014, which is herebyincorporated by reference in its entirety.

BACKGROUND

1. Field of the Invention

This application relates generally to methods and devices for repairingan intervertebral disc. More specifically, the application relates to apercutaneously deployed implantable disc replacement and methods formanufacturing such a disc replacement/prosthesis.

2. Description of Related Art

A common medical issue is back pain due to spinal disc injuries causedby trauma, the aging process or other disorders. One method of treatmentthat has been proposed is to remove the existing nucleus pulposus andreplace it with a nuclear prosthesis formed in situ using open surgeryor minimally invasive surgical techniques. One proposed method comprisesthe steps of (i) providing a mold, such as a balloon, to contain aflowable curable material that can cure in situ within the disc space,(ii) providing a conduit to connect the mold cavity to a source offlowable curable material, (iii) delivering the flowable curablematerial into the mold to fill the cavity, and (iv) permitting thecurable material to cure.

The existing techniques for forming a nuclear prosthesis in situ havenot achieved convincing clinical acceptance or commercial success. Oneproblem identified by the present inventors is the substantialdifference in the modulus of elasticity between the vertebral bonyelements, including the vertebral end plates, and the annulus fibrosuson the one hand, and the implanted elements on the other. The highmodulus of elasticity of the implanted material is disadvantageous sinceit does not dampen impacts or sudden increases in intradiscal pressureduring extreme bending or torsion, especially during high loading peaks.The large difference in the modulus of elasticity between implanted discmaterials and adjacent tissues can also lead to softening of thevertebral end plates and adjacent bone (spongeosus), resulting insubsidence of the nuclear implant. Migration and expulsion of theimplant can also occur.

Therefore, there is a need for an improved nuclear implant.

SUMMARY

An object of exemplary embodiments of the present invention is toprovide a method of manufacturing an elastomeric enclosure for amulti-chamber nuclear implant that can selectively and controllably beinflated and deflated with materials that, together, provide physicaland mechanical properties similar to those of a normal disc, and whichcan be tailored to individual patient parameters.

Another object of exemplary embodiments of the present invention is toprovide a method of fabricating a nuclear implant that can be deployedpercutaneously in a disc cavity and inflated to conform to the shape andsize of the disc cavity.

A further object of exemplary embodiments of the present invention is toprovide a nuclear implant which reinforces the annulus fibrosus if it istorn.

According to an exemplary embodiment, an implantable prosthetic devicecomprises an inner inflatable enclosure having a first opening and anouter inflatable enclosure having a first opening. The outer inflatableenclosure encapsulates the inner inflatable enclosure. A valve assemblysealingly couples the first opening of the outer inflatable enclosureand the first opening of the inner inflatable enclosure, and the valveassembly is configured to allow independent inflation of the outer andinner inflatable enclosures. An annular reinforcement band is providedaround the periphery of the outer inflatable enclosure. When implanted,the inner chamber is filled with a compressible material and the outerinflatable enclosure is filled with an in situ curable material, such assilicone. This structure allows for vertical and horizontal loadstresses placed on the implant to be redirected inward, centrally towardthe inner compressible enclosure instead of outward.

The inner and outer inflatable enclosures may comprise a seamless,unitary piece of material. The inner inflatable enclosure may have asecond opening generally opposite of the first opening, the outerinflatable enclosure may have a second opening generally opposite of thefirst opening, and a plug may sealingly couple the second opening of theinner inflatable enclosure and the second opening of the outerinflatable enclosure. The plug may be coupled to a neck portion of thesecond opening of the outer inflatable enclosure. The plug and the neckportion of the second opening of the outer inflatable enclosure may becoupled to a neck portion of the second opening of the inner inflatableenclosure.

The annular reinforcement band may be placed into the second opening ofthe inner inflatable enclosure and then the distal plug may be insertedinto the second opening to couple the reinforcement band to the balloon.The reinforcement band may be coupled to the inflatable enclosure atonly one location, such as at the plug. A fastener may be provided tofasten the reinforcement band to the plug. The reinforcement band mayinclude a shape memory material. The annular reinforcement band maycomprise a tubular braid enclosing the shape memory material.

The valve assembly may comprise a valve core coupling the first openingsof the outer and inner inflatable enclosures. The valve core has anopening from an interior of the valve core to an exterior of the valvecore. A valve membrane partially envelops the valve core and has anopening into the outer inflatable enclosure. The opening in the valvemembrane and the valve core are separated from one another to allowmaterial to flow into the outer inflatable enclosure, while preventingbackflow. The valve core may further comprise a resealable, puncturablemembrane to provide access to the inner inflatable enclosure.

The valve membrane and the valve core may be integrally molded, or thevalve core may be bonded to the valve membrane with an adhesive.

The inner and outer inflatable enclosures may comprise an elastomer,such as silicone rubber.

In some embodiments, a curable material may be provided to inflate theouter inflatable enclosure, and a compressible material such as gas maybe provided to inflate the inner inflatable enclosure to allow the curedmaterial to deform. The cured material may substantially surround theinner inflatable enclosure. In other embodiments, an incompressiblematerial (e.g., a liquid) is provided to inflate the inner inflatableenclosure and then the curable material is injected into the outerinflatable enclosure. The incompressible material is then removed fromthe inner inflatable enclosure and replaced with a compressible material(e.g., a gas). In certain embodiments, the curable material furtherpolymerizes with the inner and outer inflatable enclosures to form asolid, unitary member.

In accordance with an exemplary embodiment, a valve assembly forinflating an implantable prosthetic device comprising an innerinflatable enclosure connected to an outer inflatable enclosurecomprises an elastomeric membrane forming a passageway from an interiorof the inner inflatable enclosure to an exterior of the outer inflatableenclosure and a valve core disposed in the passageway so that theelastomeric membrane surrounds the valve core. The elastomeric membranehas an opening into an interior of the outer inflatable enclosure, andthe elastomeric membrane surrounds the valve core. The valve corecomprises a conduit extending from a first end to a second end, and aresealable, puncturable membrane at the second end of the valve coreconduit for providing resealable access to the inner inflatableenclosure. An opening in the conduit extends from an interior of theconduit to an exterior of the conduit, and the opening in the valve coreis offset from the opening in the elastomeric membrane to form a one wayvalve allowing material introduced into the interior of the conduit topass into the interior of the outer inflatable enclosure whilepreventing backflow.

In accordance with an exemplary embodiment, a method of implanting aprosthetic device into an intervertebral space having a nucleus pulposussurrounded by an annulus fibrosus comprises penetrating the annulusfibrosus, removing the nucleus pulposus, and implanting an implantableprosthetic device, wherein the implantable prosthetic device comprisesan inner inflatable enclosure having a first opening and an outerinflatable enclosure having a first opening. The outer inflatableenclosure encapsulates the inner inflatable enclosure. A valve assemblysealingly couples the first opening of the outer inflatable enclosureand the first opening of the inner inflatable enclosure, and the valveassembly is configured to allow independent inflation of the outer andinner inflatable enclosures. A reinforcement band is provided around theperiphery of the outer inflatable enclosure.

In some embodiments, the method may further comprise inflating the innerinflatable enclosure using a compressible material, and the compressiblematerial may comprise a gas. The method may further comprise inflatingthe outer inflatable enclosure using a curable material, and the curablematerial may be silicone rubber. In other embodiments, the method mayfurther comprise inflating the inner inflatable enclosure using anincompressible material, and the incompressible material may comprise aliquid. The method may further comprise inflating the outer inflatableenclosure using a curable material, allowing the curable material tocure, and then replacing the incompressible material in the innerinflatable enclosure with a compressible material.

In accordance with an exemplary embodiment, a method of producing animplantable prosthetic device comprises (i) injection molding aprosthesis blank comprising an outer membrane section with a proximalend and a distal end, an inner membrane section with a proximal end anda distal end, a valve section disposed between the proximal end of theouter membrane section and the proximal end of the inner membranesection, a distal plug inner section at the distal end of the innermembrane section, and a distal plug outer section at the distal end ofthe outer membrane section; and (ii) partially inverting the prosthesisblank so that the outer membrane section encloses the inner membranesection to form an outer balloon surrounding an inner balloon formed bythe inner membrane.

In accordance with an exemplary embodiment, a method of producing animplantable prosthetic device comprises (i) providing a mandrel with aprofiled outer surface configured to form a prosthesis blank comprisingan outer membrane section with a proximal end and a distal end, an innermembrane section with a proximal end and a distal end, a valve sectiondisposed between the proximal end of the outer membrane section and theproximal end of the inner membrane section, a distal plug inner sectionat the distal end of the inner membrane section, and a distal plug outersection at the distal end of the outer membrane section; (ii) coatingthe mandrel with a material to form the prosthesis blank; (iii)stripping the prosthesis blank from the mandrel; and (iv) partiallyinverting the prosthesis blank so that the outer membrane sectionencloses the inner membrane section to form an outer balloon surroundingan inner balloon formed by the inner membrane.

The mandrel may comprise a unitary body, and the valve section of themandrel may comprise a valve core that is integrally molded with theprosthesis blank. The mandrel may comprise two separable pieces coupledto the valve core, and the step of stripping the prosthesis blank fromthe mandrel may comprise separating the mandrel pieces from the valvecore and removing the separable pieces from the prosthesis blank.

The valve core may be glued into the valve section.

The distal plug may be inserted into the distal plug outer section toseal the distal plug outer section, and the distal plug and distal plugouter section may be inserted into the distal plug inner section.

A reinforcing band may be joined to the distal plug, and the reinforcingband, distal plug, and distal plug outer section may be inserted intothe distal plug inner section. The reinforcing band may be joined to thedistal plug with a fastener.

The mandrel may be coated by dipping it into a polymer liquid, which maycomprise a silicone dispersion, and dried.

The elastomeric membrane may be stripped from the mandrel by melting themandrel, or the prosthesis blank may be removed from the mandrel bystretching it over the mandrel. A reinforcing band may be applied aroundthe periphery of the outer balloon.

In accordance with an exemplary embodiment, a mandrel for producing animplantable prosthetic device comprises a first balloon mandrel with aprofiled outer surface configured in the shape of a first balloon; asecond balloon mandrel with a profiled outer surface configured in theshape of a second balloon; and a valve core disposed between the firstand second balloon mandrels. The outer surface of the first balloonmandrel may further comprises a distal opening section, and the outersurface of the second balloon mandrel may further comprise a distalopening section. The outer surfaces of the balloon mandrels may becurved. The outer surfaces of each of the balloon mandrels may comprisea central section with a generally uniform diameter.

In accordance with an exemplary embodiment, a mandrel for producing animplantable prosthetic device comprises a unitary body with a profiledouter surface. The profiled outer surface has an outer membrane sectionconfigured to form an annular balloon with a proximal end and a distalend; an inner membrane section configured to form a nuclear balloon witha proximal end and a distal end; a valve section configured to receive avalve assembly disposed between the proximal end of the outer membranesection and the proximal end of the inner membrane section; a distalplug outer section configured to receive a distal plug at the distal endof the outer membrane section; and a distal plug inner sectionconfigured to receive an assembly of the distal plug and distal plugouter section at the distal end of the inner membrane section.

The term “coupled” is defined as connected, although not necessarilydirectly. The terms “a” and “an” are defined as one or more unless thisdisclosure explicitly requires otherwise. The terms “substantially,”“approximately,” and “about” are defined as largely but not necessarilywholly what is specified (and includes what is specified; e.g.,substantially 90 degrees includes 90 degrees and substantially parallelincludes parallel), as understood by a person of ordinary skill in theart. In any disclosed embodiment, the terms “substantially,”“approximately,” and “about” may be substituted with “within [apercentage] of” what is specified, where the percentage includes 0.1, 1,5, and 10 percent.

The terms “comprise” (and any form of comprise, such as “comprises” and“comprising”), “have” (and any form of have, such as “has” and“having”), “include” (and any form of include, such as “includes” and“including”) and “contain” (and any form of contain, such as “contains”and “containing”) are open-ended linking verbs. As a result, a system,or a component of a system, that “comprises,” “has,” “includes” or“contains” one or more elements or features possesses those one or moreelements or features, but is not limited to possessing only thoseelements or features. Likewise, a method that “comprises,” “has,”“includes” or “contains” one or more steps possesses those one or moresteps, but is not limited to possessing only those one or more steps.Additionally, terms such as “first” and “second” are used only todifferentiate structures or features, and not to limit the differentstructures or features to a particular order.

A device, system, or component of either that is configured in a certainway is configured in at least that way, but it can also be configured inother ways than those specifically described.

Any embodiment of any of the systems and methods can consist of orconsist essentially of—rather than comprise/include/contain/have—any ofthe described elements, features, and/or steps. Thus, in any of theclaims, the term “consisting of” or “consisting essentially of” can besubstituted for any of the open-ended linking verbs recited above, inorder to change the scope of a given claim from what it would otherwisebe using the open-ended linking verb.

The feature or features of one embodiment may be applied to otherembodiments, even though not described or illustrated, unless expresslyprohibited by this disclosure or the nature of the embodiments.

Details associated with the embodiments described above and others arepresented below.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of an inflated implant in accordance withan embodiment of the present invention;

FIG. 2 is a perspective view of the inflated implant of FIG. 1 fromanother direction;

FIG. 3 is a top view of the implant of FIG. 1;

FIG. 4 is a sectional view taken through line 4-4 in FIG. 2;

FIG. 5 is a sectional view taken through line 5-5 in FIG. 2;

FIG. 6 is a cut-away view of a portion of an implant valve of theimplant of FIG. 1;

FIG. 7 is a cut-away view of a portion of the implant valve of FIG. 6;

FIG. 8 is a sectional view of an implant assembly prior to insertion ofa distal plug and attachment of an annular reinforcing member;

FIG. 9 is a sectional view of a mandrel and implant according to anembodiment of the present invention;

FIG. 10 illustrates a first assembly step for the implant assembly ofFIG. 1;

FIG. 11 illustrates a second assembly step for the implant assembly ofFIG. 1;

FIG. 12 illustrates a third assembly step for the implant assembly ofFIG. 1;

FIG. 13 illustrates a fourth assembly step for the implant assembly ofFIG. 1;

FIG. 14 is a sectional view of a mandrel and implant assembly accordingto another embodiment of the present invention;

FIG. 15 illustrates a first assembly step for the implant assembly ofFIG. 1;

FIG. 16 illustrates a second assembly step for the implant assembly ofFIG. 1;

FIG. 17 illustrates a third assembly step for the implant assembly ofFIG. 1;

FIG. 18 illustrates a fourth assembly step for the implant assembly ofFIG. 1;

FIG. 19 illustrates a final assembly step for the implant assembly ofFIG. 1;

FIG. 20 illustrates a first step in implanting the implant assembly ofFIG. 1;

FIG. 21 illustrates a second step in implanting the implant assembly ofFIG. 1;

FIG. 22 illustrates a third step in implanting the implant assembly ofFIG. 1; and

FIG. 23 illustrates a fourth step in implanting the implant assembly ofFIG. 1.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, in which are shown exemplary but non-limiting andnon-exhaustive embodiments of the invention. These embodiments aredescribed in sufficient detail to enable those having skill in the artto practice the invention, and it is understood that other embodimentsmay be used, and other changes may be made, without departing from thespirit or scope of the invention. The following detailed description is,therefore, not to be taken in a limiting sense, and the scope of theinvention is defined only by the appended claims. In the accompanyingdrawings, like reference numerals refer to like parts throughout thevarious figures unless otherwise specified.

Description of Implant

Referring to FIGS. 1-8, an embodiment of a percutaneously deliverablespinal implant 100 includes an outer inflatable enclosure (or balloon)102 and an inner inflatable enclosure (or balloon) 104. Outer inflatableenclosure 102 forms an annular chamber 106, and inner inflatableenclosure 104 forms a nuclear chamber 108. Nuclear chamber 108 isencapsulated within annular chamber 106. Preferably, outer and innerinflatable enclosures 102, 104 are formed as a seamless, unitary pieceof an elastomeric material, such as silicone rubber. The use of anelastomeric material produces compliant outer and inner balloons 102,104. That is, the outer and inner balloons 102, 104 expand when internalpressure is applied. The use of compliant balloons provides certainadvantages. Compliant balloons accommodate the irregular, flat ordiscoid configuration of the nuclear space. Furthermore, a compliantballoon maintains an appropriate modulus of elasticity of the nuclearimplant following elastomeric curing, and preserve bio-mechanicalmobility of the vertebral segment, and allows unhindered deformation ofthe cured silicone component into the central void.

An annular reinforcing band 110 may be disposed around the perimeter ofthe lateral edges of implant 100 to minimize or prevent over-stretchingof the elastomeric membrane or over inflation of outer and innerballoons 102, 104 circumferentially. Annular reinforcement band 110encourages vertical expansion to widen the disc space. The vertebralsuperior and inferior end plates constrain the expansion of the implant100.

The size of implant 100 is selected so that it can be percutaneouslyinserted into a denucleated intervertebral disc space while deflated andthen inflated to fill the denucleated cavity. In one embodiment, theexterior of inflated implant 100 is approximately 30 mm in length, 20 mmin width, and 10 mm in height, and the exterior of inner inflatableenclosure 104 is approximately 9 mm long, 6 mm wide, and 6 mm thick.

Annular reinforcing band 110 may be a biocompatible textile material. Inone embodiment, annular reinforcing band 110 comprises a tubular, woventextile material. Annular reinforcing band 110 may also include anexpandable member to provide additional support. The expandable membermay be formed of a shape memory material, such as nitinol. U.S. Pat. No.8,636,803, entitled Percutaneous Implantable Nuclear Implant, disclosesone suitable construction of annular reinforcing band 110, and is herebyincorporated by reference in its entirety for all purposes.

Outer inflatable enclosure 102 has a first opening 118 and a secondopening 120. Inner inflatable enclosure 104 has a first opening 136 anda second opening 138. A proximal plug, or valve core, 112 connects firstopening 118 and first opening 136. A valve membrane 122 surroundsproximal plug 112 and cooperates with proximal plug 112 to form aninflation valve 124. Inflation valve 124 is a one-way valve which allowsmaterial to be introduced into annular chamber 106. Preferably, valvemembrane 122 is formed integrally with outer and inner inflatableenclosures 102, 104, as will be described in further detail below. Asseen most clearly in FIGS. 6-8, proximal plug 112 comprises a conduit126 extending from a first end 128 to a second end 130. First end 128 ofproximal plug 112 forms a port 114 for receiving an inflation stylus116. Valve membrane 122 is coupled to proximal plug 112 by first andsecond adhesive bands 140, 142, which are substantially fluid tight. Theportion of valve membrane 122 between first and second adhesive bands140, 142 is unbonded to form a channel for allowing material to flowtherethrough. At least one opening 132 extends from conduit 126 to theexterior of proximal plug 112. Valve membrane 122 has at least oneopening 134 which is offset from opening 132. In this manner, when asuitable material (described in detail below) is introduced into conduit126 under pressure, the material is introduced through opening 132 intoannular chamber 106, stretches valve membrane 122, and flows out throughopening 134. When pressure is removed from conduit 126, valve membrane122 seals opening 132 and prevents backflow through opening 132. Secondend 130 of conduit 126 is closed by a puncturable, resealable membrane144.

A distal plug 146 is disposed in a neck portion 148 extending fromsecond opening 138 of the inner inflatable enclosure 104. The distalplug 148 is bonded to the neck portion 148 to form a fluid tight seal.The distal plug 146 and neck portion 148 assembly is disposed within aneck portion 150 extending from second opening 120 of outer inflatableenclosure 102. Annular reinforcing band 110 may be trapped between thedistal plug 146 and neck portion 148 assembly and the neck portion 150to serve as an anchor for reinforcing band 110. Alternatively, afastener 152 may be used to anchor annular reinforcing band 110 todistal plug 146, as seen most clearly in FIG. 9.

Method of Manufacturing the Implant

Referring to FIGS. 9-13, in one embodiment, inner and outer inflatableenclosures 102, 104 are formed from a unitary implant blank 154. Implantblank 154 may be produced by dip molding using a mandrel 156. Mandrel156 comprises an outer membrane section 158, an inner membrane section160, and a valve section 162. Mandrel 156 may be one piece or multiplepieces. In one embodiment, outer membrane section 158, inner membranesection 160, and valve section 162 are separate pieces which areassembled together. Mandrel 156 is dipped into a polymer liquid, such asa silicone dispersion, removed from the liquid and allowed to dry orcure. Mandrel 156 may be dipped one or more times to build up a desiredthickness of material. The blank 154 comprises neck portion 150, outerinflatable enclosure 102, valve membrane 122, inner inflatable enclosure104, and neck portion 148.

After curing or drying, implant blank 154 is stripped from mandrel 156.This may be accomplished by stretching implant blank 154 over mandrel156. If mandrel 156 is composed of separable pieces, it may bedisassembled prior to stripping. In one embodiment, mandrel 156 may beformed of a meltable or dissolvable material and melted or dissolved tostrip implant blank 154 from mandrel 156. Opening 134 through valvemembrane 122 is formed in implant blank 154.

Referring to FIGS. 10-13, implant blank 154, distal plug 146 andproximal plug (or valve core) 112 are provided. Neck portion 148 whichextends from inner inflatable enclosure 104 is inverted into theinterior of inner inflatable enclosure 104 and distal plug 146 isinserted into neck portion 148 and glued into place. The neck portion isthe further inverted into the annular chamber 106. Next, proximal plug112 is inserted and glued into the valve membrane 122. This is done intwo steps. First, the end of proximal plug 112 nearest the annularchamber 106 is glued to valve membrane 122 with first adhesive band 142.Next, the implant blank 154 is further inverted, and second adhesiveband 142 is applied to glue implant blank 154 to the second end ofproximal plug 112. This results in the configuration shown in FIG. 12.Next, neck portion 150 is tucked into outer inflatable enclosure 102 (asindicated by the arrows in FIG. 8) and over distal plug 146 and neckportion 148, as shown in FIG. 13. Annular reinforcing band 110 may betucked in at the same time, or may be fastened to distal plug 146 by afastener.

In another embodiment, implant blank 154 is formed by injection moldingover a mandrel using conventional techniques. That is, the mandrel isplaced into an injection mold having a cavity corresponding to the outershape of the implant blank, and a curable material is injected into themold under pressure. The curable material is allowed to cure, therebyforming implant blank 154 over the mandrel. The mandrel and implantblank 154 are then removed from the injection mold. Once implant blank154 is formed, the remaining assembly steps are as described in theprior paragraph.

FIGS. 14-19 illustrate another method of making an implant 100. In thisembodiment, a mandrel 164 comprises a first mandrel section 166 formingan outer membrane section 168 and a second mandrel section 168 formingan inner membrane section 170. First mandrel section 166 is insertedinto valve core (or proximal plug) 112, and second mandrel section ismated with the other end of proximal plug 112. Referring to FIG. 15, themandrel and valve assembly is then dip molded to form an implant blank176. Referring to FIG. 16, the neck portion 188 of the implant blank 176is inverted and a proximal plug is glued into the neck portion 188. Avalve membrane 192 is applied over the plug section and adhered to theplug section with first and second adhesive bands to form an implantvalve. The implant blank 176 is then inverted left to right over thevalve core 112, as shown in FIG. 18. Finally, the neck portion 190tucked into the outer inflatable enclosure 102. Annular reinforcing band110 may be tucked in at the same time, or may be fastened to distal plug146 by a fastener.

Method of Deploying an Implant

Referring to FIGS. 20-23, the inflatable implant 100 is particularlywell suited for deployment using minimally invasive or percutaneoussurgical techniques. To prepare the inflatable implant 100 fordeployment, the implant is deflated and stretched to minimize itscross-sectional profile. An insertion stylus 116 is detachably insertedinto port 114, then the implant 100 is inserted into a deploymentcannula 180. Deployment cannula 180 has a minimal cross-sectionalprofile.

Referring to FIG. 20, to implant the inflatable implant 100, theexisting nucleus pulposus is removed by performing a discectomy whileleaving the annulus fibrosus 178 substantially intact. Preferably, thediscectomy is performed using minimally invasive surgical techniques,such as percutaneous techniques, which leaves a small opening throughthe annulus fibrosus 178. Once the nucleus pulposus has been removed,the annulus fibrosus 178 and vertebral end plates 182, 184 form asubstantially empty disc cavity 182.

After the nucleus pulposus has been removed, deployment cannula 180 withpreloaded implant 100 is placed into the empty disc cavity 182. Theimplant 100 is deployed by pushing it out of the deployment cannula andinto the empty disc cavity, as shown in FIG. 21. The implant 100 is inan uninflated state.

In one embodiment, nuclear chamber 108 is first inflated with acompressible fluid 194, such as a gas. This may be performed using aneedle (not shown) which is delivered through the inflation stylus 116and pushed through the puncturable, resealable membrane 144. Thecompressible fluid is deployed into the nuclear chamber 108 to inflatethe inner inflatable enclosure 104. The pressure of the nuclear chamber108 is selected so that it provides a buffer zone for inward deformationof the cured elastomer 186 during weight bearing and spine movement.Once nuclear chamber 108 is inflated to the desired pressure, the needleis withdrawn from nuclear chamber 108. In another embodiment, instead ofusing a removable needle, inflation stylus 116 may have a septumextending through the stylus to divide the stylus into two lumens. Onelumen extends through resealable, puncturable membrane 144 into nuclearchamber 108, while the other lumen delivers an in situ curable materialto implant valve 124 and annular chamber 106.

Inflation stylus 116 is used to deliver an in situ curable material toannular chamber 106 through the one way implant valve 124 (FIG. 22). Thecurable material is preferably an elastomeric material, such as siliconerubber, which further polymerizes with the material of inner and outerinflatable enclosures 102, 104 to form a unitary member. The modulus ofelasticity and other characteristics of the curable material can beselected based upon patient specific parameters. For instance, younger,more active patients may require a firmer material than less mobilegeriatric patients. Once annular chamber 106 is inflated to a desiredpressure, inflation stylus 116 can be removed. Implant valve 124prevents the curable material from leaking out of the annular chamber106.

After the curable material is allowed to cured, the implant 100comprises an annular ring of a cured elastomer 186 surrounding nuclearchamber 108 which is filled with a compressible material 194. Thisstructure allows for vertical and horizontal load stresses placed on theintervertebral disc space to be redirected inward, centrally towardnuclear chamber 108 (see direction arrows of FIG. 23) instead ofoutward. Moreover, annular reinforcing band 110 encourages tissuein-growth of native annulus fibrosus 178, thereby providingreinforcement to native annulus fibrosus 178.

In another embodiment, nuclear chamber 108 is first inflated with anincompressible fluid, such as a liquid. This may be performed using aneedle or an inflation stylus, as described above. Once nuclear chamber194 is inflated, inflation stylus 116 is used to deliver an in situcurable material to annular chamber 106 through the one way implantvalve 124. After the curable material is allowed to cured, theincompressible fluid is removed from nuclear chamber 108 and replacedwith compressible material 194. This may be accomplished with a needleusing implant valve 124.

The above specification and examples provide a complete description ofthe structure and use of exemplary embodiments. Although certainembodiments have been described above with a certain degree ofparticularity, or with reference to one or more individual embodiments,those skilled in the art could make numerous alterations to thedisclosed embodiments without departing from the scope of thisinvention. As such, the various illustrative embodiments of the presentdevices are not intended to be limited to the particular formsdisclosed. Rather, they include all modifications and alternativesfalling within the scope of the claims, and embodiments other than theone shown may include some or all of the features of the depictedembodiment. For example, components may be combined as a unitarystructure, and/or connections may be substituted (e.g., threads may besubstituted with press-fittings or welds). Further, where appropriate,aspects of any of the examples described above may be combined withaspects of any of the other examples described to form further exampleshaving comparable or different properties and addressing the same ordifferent problems. Similarly, it will be understood that the benefitsand advantages described above may relate to one embodiment or mayrelate to several embodiments.

The claims are not intended to include, and should not be interpreted toinclude, means-plus- or step-plus-function limitations, unless such alimitation is explicitly recited in a given claim using the phrase(s)“means for” or “step for,” respectively.

The invention claimed is:
 1. A method of producing an implantableprosthetic device comprising: forming a prosthesis blank comprising: anouter membrane section with a proximal end and a distal end, an innermembrane section with a proximal end and a distal end, a valve sectiondisposed between the proximal end of the outer membrane section and theproximal end of the inner membrane section, wherein the valve sectioncomprises a conduit having a sidewall with at least one openingextending through the sidewall; a distal plug inner section at thedistal end of the inner membrane section, and a distal plug outersection at the distal end of the outer membrane section; and partiallyinverting the prosthesis blank so that the outer membrane sectionencloses the inner membrane section so that the outer membrane sectionforms an outer balloon surrounding an inner balloon formed by the innermembrane section.
 2. The method of claim 1, further comprising:providing a mandrel with a profiled outer surface configured to form theprosthesis blank; coating the mandrel with a material to form theprosthesis blank; and stripping the prosthesis blank from the mandrel.3. The method of claim 2, wherein the mandrel comprises two separablepieces coupled to a valve core.
 4. The method of claim 3, wherein thevalve core is integrally molded with the prosthesis blank.
 5. The methodof claim 4, wherein the step of stripping the prosthesis blank from themandrel comprises separating the mandrel pieces from the valve core andremoving the separable pieces from the prosthesis blank.
 6. The methodof claim 2, wherein coating the mandrel comprises dipping the mandrelinto a polymer liquid.
 7. The method of claim 2, wherein stripping theprosthesis blank from the mandrel comprises removing the materialcoating the mandrel.
 8. The method of claim 1, further comprisinginserting a distal plug into the distal plug outer section to seal thedistal plug outer section.
 9. The method of claim 8, further comprising:joining a reinforcing band to the distal plug; inserting the reinforcingband, distal plug, and distal plug outer section into the distal pluginner section.
 10. The method of claim 9, wherein the reinforcing bandis joined to the distal plug with a fastener.
 11. The method of claim 8,further comprising inserting the distal plug and distal plug outersection into the distal plug inner section.
 12. The method of claim 1,wherein the prosthesis blank is formed by injection molding.
 13. Themethod of claim 1, further comprising gluing a valve core into the valvesection.
 14. The method of claim 1, further comprising applying areinforcing band around the periphery of the outer balloon.